JP3007894B2 - Automatic tracking method of outer peripheral welding device for thin metal plate, and method of judging welding quality of outer peripheral welding device of thin metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer peripheral welding apparatus for a thin metal plate, and more particularly to an automatic follower for detecting a deviation amount between a welding torch and a proper welding position by using an image processing device and following the proper welding position. The present invention relates to a method for automatically following an outer peripheral welding device for a thin metal plate to which an apparatus is added, and a method for judging the welding state of the outer peripheral welding device for a thin metal disk.

[0002]

2. Description of the Related Art As an example of outer peripheral welding of a thin metal plate, it is used, for example, in a connection portion between a camera body and a lens.
Bellows (bellows) with a mechanism that can expand and contract in the axial direction are composed of flat and donut-shaped ring discs, each of which is brought into contact with each other and stacked coaxially. Manufactured by alternating welding.
The bellows expand and contract in the axial direction as a whole as each of the welded ring machines bends.

In order to weld the outer peripheral edges of a ring machine constituting such a bellows, a ring-shaped work is laminated and the cylindrical work is placed horizontally, and the work is held on a work table by a shaft rotating means. Welding is performed by approaching the welding torch almost perpendicularly to the outer peripheral surface. The welding is performed by rotating the work at a constant speed while maintaining this state. One round of welding of the outer peripheral edge of the ring disc is welding for one pitch. The welding torch is supported by a support base arranged on a work table, and can be moved in parallel in XYZ directions by driving means.

Here, the X direction is the axial direction of the work parallel to the work table, and the Y direction is the X direction parallel to the work table.
The direction perpendicular to the direction and the Z direction mean a direction perpendicular to the work table, and are used in this specification. When started, the conventional bellows outer peripheral welding device rotates the work during welding, and adjusts the injection position of the welding arc manually, that is, while checking the operator's eyes, to adjust the injection position of the welding arc for one pitch. Welded. When this one-pitch welding is completed, a work step of moving in the X direction by one pitch manually or automatically is employed.

[0005]

However, in the conventional bellows outer periphery welding apparatus having the above-described structure, the pitch movement can be automatically performed by setting the pitch amount in advance. Since welding of the outer peripheral surface of the ring machine relied on manual operation by an operator, this required a great deal of skill in the work. In addition, since there are many parts that depend on human work, the processing accuracy of products also varies, which not only reduces the yield, but also raises a serious problem from the viewpoint of improving work efficiency.

[0006] Furthermore, the quality of the welded state is also judged by the operator's eyes, so that it takes a lot of time to judge the quality, which also hinders workability. Furthermore, one bellows outer peripheral welding device has one
This has also hindered the reduction of manufacturing costs because of the need for human workers. In view of the above, the present invention has been made for the purpose of solving the above problem, and an image processing apparatus has been added so that the welding position of the outer periphery of the bellows, that is, the proper welding of the outer peripheral surface of the ring machine to be abutted. Provided are a bellows outer peripheral welding device capable of automatically causing a welding torch to follow a position, a method and an apparatus for automatically following an appropriate welding position used for the device, and a method for determining whether the welding condition of the bellows outer peripheral welding is good. .

[0007]

In order to achieve the above object, the present invention is configured as follows. A work table for holding a work of a thin metal plate laterally and rotatably holding the work, a welding torch disposed above the work table and injecting a welding arc to a welding position of the work for rotating the shaft, and a welding torch And a support base arranged on the work table, supporting the workpiece so as to be able to move in parallel in the XYZ directions. Image photographing means which is arranged on the near side of the work rotation direction and gazes near the welding position from a substantially tangential direction of the outer peripheral edge of the work, and based on the photographed image from the image photographing means, the welding arc to be injected and the appropriateness of the work Detecting means for detecting a displacement between the welding position in the X direction and the Z direction, and a welding torch being finely moved in the X direction and the Z direction by a signal from the detecting means so as to move over the proper welding position. Is characterized by comprising moving means for slave, the.

[0008] In addition to this, an image photographing means which is arranged on the front side in the work rotation direction with respect to the welding position of the work and gazes at a substantially perpendicular to the welded surface of the work, and a photographing means from the image photographing means. An inspection unit for inspecting a welding state based on an image, and a storage unit for storing information on the quality of welding from the inspection unit are provided.

The automatic tracking method for an appropriate welding position used in the outer peripheral welding apparatus for a thin metal plate is performed by taking an image of an injection type of a welding arc light to a welding position, and conforming the captured image to various standards of the thin metal plate. By comparing the template image with the corresponding graduation window, the displacement between the welding arc light and the proper welding position is detected, and the welding torch is moved in the X and Z directions based on the detected information. It is characterized in that it is moved by a small amount as appropriate to follow an appropriate welding position.

[0010] Further, the apparatus includes an image photographing means which is disposed on the near side in the rotational direction from the welding position of the work and which gazes at the vicinity of the welding position from a substantially tangential direction of the outer peripheral edge of the work; Storage means for storing various template information defining a scale window,
Detecting means for comparing an image signal from the image photographing means with predetermined template information output from the storage means, and detecting a deviation amount between a welding arc light and an appropriate welding position;
Moving means for causing the welding torch to slightly move in the X direction and the Z direction according to a signal from the detecting means so as to follow an appropriate welding position.

Further, in the method for judging whether the welding condition is good or bad, which is used in the outer peripheral welding device for bellows, the welded portion immediately after welding is continuously photographed by the image photographing means, and for each of the photographed images that do not overlap, The image is divided into a plurality of inspection windows continuous in the moving direction, and the area ratio between the welded portion in the inspection window and the outer peripheral surface of the ring machine is calculated,
By comparing the area ratio with a preset area ratio for good welding, the quality of the welding state is determined for each inspection window.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, as an embodiment of an outer peripheral welding device for a thin metal plate according to the present invention, a case where the present invention is applied to an outer peripheral welding device for a bellows will be described in detail with reference to the drawings. FIG. 1 is a side view of an outer peripheral welding device for the bellows of the present application, and FIG.
FIG. 4 is a side view showing the main part. FIG. 3 is an enlarged view of a main part showing the positional relationship between the outer peripheral edge of the bellows and the welding torch from the front. Note that the Y direction defined above corresponds to FIGS.
, The Z direction is displayed as the vertical direction, and the X direction is displayed as the direction perpendicular to the paper surface (the horizontal direction in FIG. 3).

The work 1 to be processed by the outer peripheral welding device for bellows includes a substantially flat and donut-shaped ring machine 2.
The surfaces are in contact with each other, and a plurality of them are coaxially laminated to form a substantially cylindrical shape. The work 1 is placed on the upper surface 3s of the work table 3 with the shaft placed horizontally (in the X direction), and is held by a scroll chuck 4 so that the shaft can be rotated. This work 1 held rotatably
The shaft is appropriately rotated by an inverter-controlled motor (not shown) connected to the scroll chuck 4.

A pair of guide rails 5, 5 are laid on the upper surface 3s of the work table 3 in parallel with the work 1 (along the X direction), and a support base 6 is mounted on the guide rails 5. It is mounted so that it can slide and straddle it. The support base 6 is guided by a guide rail 5 by a servo-controlled motor 7 and is configured to be movable in parallel with the work 1, that is, in the X direction.

A support 8 is integrally formed on the support base 6. The support 8 extends in the Y direction at a certain height from the upper surface 3 s of the work table 3 and in the vicinity of the work 1. It is formed in a rectangular shape extending up to. Support 8
Is formed with a pair of guide rails 9, 9 extending vertically and parallel to a vertical plane along the ZY plane. A substantially rectangular Y-direction moving base 10 is provided on the guide rail 9.
It is mounted so as to be movable in the Y direction. The Y-direction moving base 10 is appropriately moved in the Y-direction while being guided by the guide rail 9 by the driving of the ball screw 11 and the motor 12 screwed on the back side in FIG.

The Y-direction moving base 10 is attached at a predetermined angle (θ) in the Y direction from the Z direction.
A pair of guide rails 13, 13 extending in parallel along the tilt direction are formed on a vertical plane along the ZY plane. A substantially rectangular Z-direction moving base 14 is attached to the guide rail 13 so as to be movable in the Z-direction.

The Z-direction moving base 14 is appropriately moved in the Z-direction while being guided by the guide rail 13 by the driving of a motor 16 and a ball screw 15 screwed on the back side in FIG. In this case, the Z-direction moving base 14
Is attached to the Y-direction moving base 10 at an inclination angle (θ), so that it does not move vertically but translates vertically along a direction inclined by θ from the vertical.

Below the Z-direction moving base 14, a television camera 17 is mounted as a follow-up image photographing means. An arm 18 extending to the work 1 is attached to the work 1 side of the Z-direction moving base 14, and a welding torch 19 is attached to a tip of the arm 18. I have. Further, at a position further closer to the work 1 than the welding torch 19, a television camera 20 as an image capturing means for inspection is provided with a support rod attached to a side of the Z-direction moving base 14 on the work 1 side. 21.

Here, the position setting of the following television camera 17, the welding torch 19, and the inspection television camera 20 is performed as follows. First, these three points (17,
19, 20) are installed on a ZY plane perpendicular to the X direction, that is, on a plane orthogonal to the axis of the work 1. The follow-up television camera 17 is disposed on the near side in the work rotation direction (arrow a) with respect to the welding position of the work 1, and the inspection television camera 20 is arranged in the work rotation direction (arrow a) with respect to the welding position of the work 1. ).

The welding torch 19 has the inclination angle (θ)
, The gazing axis m of the following television camera 17 is installed so as to be substantially orthogonal to the extension axis n of the welding torch 19, and the focus thereof is at the welding torch 19.
Is fitted to the tip 19t. In addition, the inspection television camera 20 is set so as to gaze slightly near the work 1 side from the tip 19t of the welding torch 19, and is focused. In the drawings, the inspection television camera 20 is installed so as to be inclined with respect to the extension axis n of the welding torch 19, and the inclination angle is appropriately set according to the positional relationship between the arm 18 and the support rod 21. Is what is done.

With the above configuration, the bellows outer peripheral welding device of the present embodiment operates as follows.
First, the Y-direction moving base 10 and the Z-direction moving base 1
The work 1 is set to the home position (the position shown by the solid line in FIG. 2), and the work 1 is mounted and held on the scroll chuck 4. next,
The motor 7 is operated to move the support base 6 until the welding torch 19 is adjusted to the welding start point position of the work 1. Here, the motor 12 is operated, and the welding torch 19
The Y-direction moving base 10 is translated in the Y direction by a predetermined amount (arrow b) so that the extension axis n of the tip portion 19t is orthogonal to the center axis o of the work 1. In this orthogonal state, the Y-direction moving base 10 is fixed, and the Y-direction movement is not performed until the welding work of the work 1 is completed.

Next, the operation of the motor 16 lowers the Z-direction moving base 14 by a predetermined amount (arrow c), and brings the welding torch 19 close to the outer peripheral surface 2e of the ring disc 2 (see FIG. 3). . The setting of the optimum position of the close position can be visually confirmed with the naked eye and set based on the experience of the operator, but it is more reliable to make a determination by test welding.

That is, the tip 19 of the welding torch 19
When t is brought closer to the outer peripheral surface 2e of the ring disc 2 around the bellows, the welding arc light 22 having a substantially circular shape (more precisely, a substantially spherical shape) wraps around the outer peripheral surface 2e, and the following television camera 17 As shown in FIG. 4A, the lower curve is distorted into a rectangular convex portion 22a and becomes a captured image 23 extending downward as shown in FIG. The determination is made by comparing the captured image 23 with a template image 24 stored and set in advance in accordance with various standards of the work (bellows) 1. In the template image 24, the scale windows 2 in the horizontal direction (X direction) arranged at predetermined intervals
5h and a scale window 25v in the vertical direction (Z direction) are created corresponding to the standard of the ring board 2 of the workpiece 1 to be processed.

From the monitor image 26 obtained by synthesizing the photographed image 23 (FIG. 4A) and the template image 24 (FIG. 4B), the scale windows 25h and 25v are used as a guide to start welding. The optimum positions of the welding torch 17 and the ring machine 2 in the X and Z directions are set. The information on the optimum position at this time is used in the following device, which will be described later, and is stored in the storage device until the work of the work 1 is completed.

When the position setting of the welding start point of the work 1 is completed, the apparatus is started. The setting of the welding start point is usually performed manually by an operator. Next, an embodiment of a method and an apparatus for automatically following a proper welding position will be described. The thickness of the ring machine 2 constituting the bellows (work) 1, the number of laminations,
Scale window 25 corresponding to various standards
Information of the various template images 24 in which h and 25v are arranged is stored in the storage unit in advance. As the storage means, for example, a ROM (read only memory; read only storage device) or the like is used. The information of the predetermined template image 24 is extracted from the storage means, and the photographed image 2
3 to form a monitor image 26 that is synthesized. With this monitor image 26, the positional relationship that changes every moment as the welding torch 19 moves is corrected.

That is, the method is as follows.
The welding arc light 22 is projected on a monitor image 26 in black and white display via a filter. If the welding torch 19
Is shifted in any of the X directions, the welding arc light 22 also shifts. Therefore, the welding arc light 22 overlaps either the left or right scale window 25h in the horizontal direction (X direction). Each scale window 25h, 25h, ...
Is a section of a minute area, and ON / OFF information is output depending on whether the area is white or black. Based on this output information, the position of the scale window 25h where the welding arc light 22 overlaps is known, and the shift amount in the X direction is detected from the information on the interval between the scale window 25h and each scale window 25h. Similarly, the shift amount in the Z direction is set in advance as the optimum position in the Z direction of the welding torch 19 described above by knowing the scale windows 25v, 25v,... Formed in the vertical direction of the monitor image 26. The deviation amount in the Z direction is detected in comparison with the information that has been performed. An arithmetic processing device such as a microcomputer is used as these detecting means.

If the detected information indicates that a displacement has occurred, the servo-controlled motor 7 and motor 16 are driven as appropriate to make small movements in the X and Z directions. In this manner, the optimum welding position of the outer peripheral surface 2e of the ring disc 2 is followed while detecting and correcting the deviation amount in the monitor image sequentially. In this manner, at the time when the entire outer periphery of the outer peripheral surface 2e of the ring disc 2 is welded (at the end of one pitch welding), the injection of the welding arc light 22 of the welding torch 19 is automatically stopped by a preset program. Let it. Then, by operating the motor 7, the support base 6 is moved by one preset pitch, and welding of the adjacent ring disc 2 is automatically started. Note that the rotation angle of the work 1 in one-pitch welding is set to (360 + α) degrees in consideration of an inspection described later.

Next, the condition immediately after welding is photographed by the inspection television camera 20 for the condition after welding, and the quality of welding is inspected based on this image. The method of determining the quality will be described below with reference to FIGS. FIG. 5 shows a photographed image of the welded portion, and FIG. 6 is an enlarged plan view showing the inspection window. First, the inspection television camera 20 gazes at the welded portion 27 immediately after welding, and continuously photographs. Next, the photographed image 29 is partitioned into a plurality of (three in this embodiment) inspection windows 30a, 30b, and 30c that are continuous in the Y direction (vertical direction in the drawing) for the projected welded portion 27, Judge about this.

This determination is made by image processing as follows. The captured image 28 is displayed in black and white, and the welded portion 27 is displayed.
Are displayed in white, and the other outer peripheral surface 2e of the ring machine is displayed in black. The area ratio between the white display portion and the black display portion is obtained. If this ratio falls between the upper limit value and the lower limit value of the ratio that can be determined to be “good” in the inspection window 29, The welding state is determined to be “good”, and other than that, it is determined to be “bad”.

As described above, the inspection windows 29 are divided into three parts and each of them is determined. For example, as shown in FIG. 6, three inspection windows 29 are determined as one determination section. In this case, the inspection window 29b having a small number of white display portions, which is obviously determined to be in a defective state, is different from the inspection windows 29a, 2a, 2
9c, the black-and-white display ratio as a whole is determined to be non-defective and falls within the area ratio range, and there is a risk that a defective welding state may be overlooked. In addition, by reducing the size of the inspection window 29, image information per unit time of the photographed image 28 determined by a sequentially controlled motor (not shown) and the video of the inspection window 29 are taken in and efficiently correspond to the arithmetic processing capability. As a result, the inspection window 29 can be set continuously on the welded portion 27.

In this way, the quality is inspected, and if there is a defect, the welding is stopped at the end of the one-pitch welding including the defect, and the operator is notified of this by some warning light. In this case, the operator searches for the defective position, corrects it, and starts the apparatus of the present embodiment again. In the above-mentioned embodiment, the outer peripheral welding device for the bellows in the turning welding of the thin metal plate has been described, but the present invention is not limited to this bellows.

[0032]

With the above configuration, the present invention has the following effects. The initial position of the welding start point and the position of the welding torch were set manually by monitoring with a tracking television camera and calculating the deviation of the welding torch from this monitor image and correcting it sequentially. Thereafter, the welding operation can be performed fully automatically.

In addition, since the quality of the welding is inspected by monitoring it with an inspection television camera, the inspection can be performed faster and more reliably than with the naked eye of the operator. As described above, the automation of the operation in which the operation of the operator is eliminated contributes to the cost reduction of the product.

[Brief description of the drawings]

FIG. 1 is a side view of a bellows outer peripheral welding device of the present embodiment.

FIG. 2 is a side view showing a main part of the bellows outer peripheral welding device of the present embodiment.

FIG. 3 is an enlarged view of a main part showing a positional relationship between an outer peripheral edge of a ring machine and a welding torch according to the embodiment from the front.

FIG. 4 is a plan view showing a monitor image from a tracking television camera of the embodiment.

FIG. 5 is a plan view showing a monitor image from the inspection television camera of the present embodiment.

FIG. 6 is an enlarged plan view showing a main part of a monitor image from the inspection television camera of the present embodiment.

[Explanation of symbols]

1 ··· Work (bellows) 2 ··· Ring machine 2
e: Outer peripheral surface 3: Work table 3s: Upper surface 4
.... Scroll chuck 5 ... Guide rail 6 ... Base 7
····· Motor 8 ··· Support 9 ··· Guide rail 10
・ ・ ・ ・ Y-direction moving base 11 ・ ・ ・ ・ Ball screw 12 ・ ・ ・ ・ Motor 13
······ Guide rail 14 ···· Z-direction moving base 15 ···· Ball screw 16
・ ・ ・ ・ Motor 17 ・ ・ ・ ・ TV camera for tracking 18 ・ ・ ・ ・ Arm 19
····· Welding torch 20 ··· TV camera for inspection 21 ··· Support rod 22
・ ・ ・ ・ Welding arc light 23 ・ ・ ・ ・ Photographed image 24 ・ ・ ・ ・ Template image 25
・ ・ ・ ・ Scale window 26 ・ ・ ・ ・ Monitor image 27 ・ ・ ・ ・ Welded part 28
.... Photograph 29 ... Inspection window

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G01N 33/20 G01N 33/20 P (72) Inventor Masaharu Chiba 1-12-1 Tsutsumicho, Aoba-ku, Aoba-ku, Sendai, Miyagi Co., Ltd. Inside Motoyama Works (72) Inventor Tatsuhei Kadota 1-12-1 Tsutsumicho, Aoba-ku, Sendai City, Miyagi Prefecture Inside Motoyama Works Co., Ltd. (56) References JP-A-63-93480 (JP, A) JP-A-64- 40176 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/127 508 B23K 9/028 B23K 9/12 331 B23K 31/00 B23K 37/047 501

Claims (2)

(57) [Claims] 1. A work table (3) for horizontally placing and holding a work (1) such as a thin metal plate so as to be rotatable about an axis, and a work (1) arranged above the work table (3) and rotated about an axis. And a welding torch (19) for injecting a welding arc to the welding position of (1), and the welding torch (19) is arranged on the work table while supporting the welding torch (19) so as to be able to move in parallel in the XYZ directions. In an outer peripheral welding apparatus for a thin metal plate composed of a support base (6) and an outer peripheral welding apparatus, an image of an injection form of a welding arc beam (22) to a welding position is taken, and the taken image (23) and a work (1) are taken. The welding arc light (2) is compared with a template image (24) in which a scale window (25) is defined in accordance with various standards.
2) A deviation amount between the welding position and the proper welding position is detected, and based on the detected information, the welding torch (19) is finely moved appropriately in the X direction and the Z direction to follow the proper welding position. Automatic follow-up method for the outer peripheral welding device for thin metal plates. 2. A work table (3) for horizontally placing a work (1) such as a thin metal plate so as to be rotatable, and a work (1) arranged above the work table (3) and rotatable about the work. And a welding torch (19) for injecting a welding arc to the welding position of (1), and the welding torch (19) is arranged on the work table while supporting the welding torch (19) so as to be able to move in parallel in the XYZ directions. In the outer peripheral welding device for a thin metal plate composed of a support base (6) and a welding part (27) immediately after welding by an image photographing means (20), the photographed image (28) For each non-overlapping image, the image is divided into a plurality of inspection windows (29) that are continuous in the moving direction, and the inspection window (2)
9) By calculating the area ratio between the welded portion (27) and the outer peripheral surface (2e) of the ring machine, and comparing the calculated area ratio with the preset area ratio for good welding, A method for determining the quality of a welding state of an outer peripheral welding device for a thin metal plate, wherein the quality of a welding state is determined for each inspection window.